Subterranean tools need to be put into position into a wellbore before they are actuated. One such tool is a packer, which is used to isolate between or among zones for a variety of reasons including well control and production. Depending on the depth that the packer is to be set and assuming no unforeseen problems in running the packer to the target depth it is possible to have a packer automatically set after an allotted time on a timer that is tied to the setting mechanism. There are a variety of known ways to set a packer such as by using wellbore hydrostatic pressure, relative movement induced in a variety of ways, expansion and inflation, to name a few ways.
Triggering such setting of the packer can involve a locking mechanism that is unlocked such as for example with a magnetic field generated by a permanent magnet that is pumped downhole using opposed packing elements 76 and 78 as shown in FIG. 1 of U.S. Pat. No. 3,264,994. In other designs a wireline delivers a permanent or electromagnet that when brought in close proximity to the tool changes the physical properties of fluid in the tool so that flow is enabled so that the tool can be set. This design is shown in US Publication 2010/0126716.
The present invention relates to tools that can be triggered to set on a timer that can be stopped if there is a problem in getting the tool into position within the preset time. The system also has the capability of having the timer restarted to count off the remaining time or to go immediately to actuate the setting mechanism for the tool. In the preferred embodiment the tool is a packer that is set with a reaction that generates gas pressure to create the movement to set the packer. The reaction is preferably initiated by the application of a magnetic field that triggers a valve to open to allow the reactants to mix to generate the gas that sets the packer. The magnetic field can be brought in close proximity with the tool with a permanent or electromagnet that can be delivered either on wireline or slickline or can be mounted internally to an object such as a ball or a plug that can reach the tool by gravity in a vertical well or can be aided in moving to the desired location with circulation. Optionally, the object transporting the magnet can land on a seat in the string that was used to place the packer to provide an emergency capability to set the packer with pressure on the seated object.
Those skilled in the art will better appreciate the details of the invention from a review of the preferred embodiment description and associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.